Question

If the centroid of triangle whose vertices are $(a,1,3)$ $(-2,b,-5)$ and $(4,7,c)$ be the origin, then the values of $a,b,c$ are

• A. $-2,-8,-2$
• B. $2,8,-2$
• C. $-2,-8,2$
• D. $7,-1,0$

Answer 1

Answer: (C)

$-2,-8,2$

$A(a,1,3)$

$B(-2,b,-5)$

$C(4,7,c)$

centroid of $\Delta$ABC will be

$(\frac{a-2+4}{3},\frac{1+b+7}{3},\frac{3-5+c}{2})=10,0$

on equating

$\frac{a+2}{3}=0$

$a=-2$

$\frac{b+8}{3}=0$

$b=-8$

$\frac{c-2}{2}=0$

$c=2$.